1. Field of the Invention
The present invention relates to a vulcanized rubber laminate obtained by firmly bonding an epichlorohydrin rubber layer to a fluororubber layer containing an organic peroxide-based vulcanizing agent.
2. Description of the Related Art
Increase of engine room temperature, recycle of exhaust gas, and fuel evaporative emission regulation have recently progressed in view of exhaust gas control and energy saving, and as a result, it has been required that rubber materials to be used therefor have thermal aging resistance, resistance to weather, sour gasoline and alcohol-containing gasoline, and low fuel permeation, etc. Rubber materials having the above properties, which can be used in fuel oil hoses, include fluororubbers. However, the fluororubbers are expensive and disadvantageously poor in cold resistance. Thus, laminates having an inner layer of a fluororubber and an outer layer of an epichlorohydrin rubber have widely been used in the hoses for fuel oils such as gasoline instead of acrylonitrile-butadiene copolymer rubbers (NBR). In the laminates of the fluororubber layers and epichlorohydrin rubber layers, vulcanizing agents for the fluororubbers have been selected from bisphenol-, polyamine-, or peroxide-based vulcanizing agents, etc. depending on the purpose of use, and now the use of the peroxide-based vulcanizing agents is expanding because the fluororubbers using them are excellent in aging resistance to the fuel oils.
In the above multilayer rubber hoses, adhesiveness between the different rubber layers is the most important subject. It is known that the fluororubber layer and epichlorohydrin rubber layer are poor in the adhesiveness to each other, and thus the rubbers are generally bonded by methods of adding additives to the epichlorohydrin rubbers, etc.
Polyol- or polyamine-based vulcanizing agents are added to the fluororubbers in Examples of JP-A-58-103555, JP-A-1-11180, JP-A-2-160867, and JP-A-9-85898, but addition of organic peroxides has not been disclosed.
A laminate using an organic peroxide- or amine-based vulcanizing agent in a fluororubber is described in JP-A-4-372652. In this laminate, the adhesiveness is poor when a vulcanizing agent other than the peroxide- or amine-based agent is used in an epichlorohydrin rubber, and a particular phosphonium salt has to be added to the epichlorohydrin rubber. Further, the epichlorohydrin rubber using the organic peroxide- or amine-based vulcanizing agent has insufficient heat resistance.